The present invention relates to a control system for an internal combustion engine and method thereof, or more in particular to a control system for controlling operating conditions of the internal combustion engine including ignition timing, air-fuel ratio and supercharge pressure by use of parameters determined according to the amount of intake air.
The amount of intake air is a basic amount of control for the internal combustion engine, and control systems for the internal combustion engine is equipped with means for detecting the amount of intake air in order to calculate the amount of fuel injection, estimate the air-fuel ratio of the mixture gas or determine the ignition timing. (See, for example, JP-A-57-28865, etc.). The most desirable configuration of the internal combustion engine for detecting the amount of intake air involved in the combustion in a cylinder is such that the mass velocity of air flowing in the intake manifold is integrated by time in the intake stroke thereby to obtain the mass amount of intake air. Such a means for detecting the amount of intake air is disclosed, for instance, in. U.S. Pat. No. 3,747,577 in which a silicon semiconductor or a hot wire such as platinum adapted for self-heating by energization is provided in a portion of uniform velocity in the intake manifold to detect the mass amount of intake air from the degree of cooling of the hot wire or the like by the intake air. An application of such a means to a control system for an internal combustion engine is under study.
In this type of internal combustion engine control system, however, the configuration of the detection means for measuring the amount of intake air as a mass flow rate is so complicated and bulky as to make practical applications thereof difficult. Another problem is that if the control system uses a microcomputer for integrating the mass flow rate over the intake stroke over the detected small section, the microcomputer operation is occupied exclusively by such a measurement.
Further, in view of the fact that the amount of intake air is detected only by integration over the intake stroke, it may sometimes be difficult to reflect the result in the control with the amount of intake air.